Transfer RNA acetylation regulates in vivo mammalian stress signaling [tRNAseq]

Transfer RNA (tRNA) modifications are crucial for protein synthesis, but their physiological roles remain poorly understood. Here we investigate the impact of N4-acetylcytidine (ac4C), a highly conserved tRNA modification, using a Thumpd1 knockout mouse model. We find that loss of Thumpd1-dependent tRNA acetylation leads to reduced levels of tRNALeu, increased ribosome stalling and collisions, and activation of eIF2 phosphorylation. Thumpd1 knockout mice exhibit growth defects and sterility. Remarkably, concurrent knockout of Thumpd1 and the stress-sensing kinase Gcn2 causes penetrant postnatal lethality, revealing a critical genetic interaction. Our findings demonstrate that a modification restricted to a single site within type II cytosolic tRNAs can regulate ribosome-mediated signaling in mammalian organisms. By providing insight into how tRNA modifications shape signaling and cell fate in response to stress, this work opens up novel strategies for therapeutic intervention and translational control. mim-tRNAseq转运RNA（transfer RNA，tRNA）修饰对蛋白质合成至关重要，但其生理功能仍有待充分阐释。本研究采用Thumpd1基因敲除小鼠模型，探究了高度保守的tRNA修饰N4-乙酰胞嘧啶（N4-acetylcytidine，ac4C）的生物学效应。研究发现，依赖Thumpd1的tRNA乙酰化缺失会导致tRNALeu水平降低、核糖体停滞与碰撞事件增多，并激活eIF2磷酸化通路。Thumpd1基因敲除小鼠表现出生长缺陷与不育表型。值得注意的是，同时敲除Thumpd1与应激感应激酶Gcn2会引发完全外显的出生后致死，揭示了二者间关键的遗传互作关系。本研究证实，仅局限于II型胞质tRNA单个位点的修饰，即可调控哺乳动物体内的核糖体介导的信号通路。本研究阐明了tRNA修饰如何响应应激并调控信号通路与细胞命运，为治疗干预与翻译调控提供了全新策略。mim-tRNAseq